Why determinism in physics has no implications for free will

TL;DR

This paper defends the view that determinism in physics does not conflict with free will, clarifies how probabilities are introduced in deterministic theories, and argues against interpreting physical parameters as properties of systems.

Contribution

It provides a comprehensive argument that determinism and free will are compatible, clarifies the role of probabilities in deterministic physics, and critiques the ontological interpretation of physical parameters.

Findings

Deterministic theories are maximally informative and simple.

Probabilities in deterministic physics reflect ignorance of initial conditions.

Physical parameters do not need to be ontologically real to explain phenomena.

Abstract

This paper argues for the following three theses: (1) There is a clear reason to prefer physical theories with deterministic dynamical equations: such theories are maximally rich in information and usually also maximally simple. (2) There is a clear way how to introduce probabilities in a deterministic physical theory, namely as answer to the question of what evolution of a specific system we can reasonably expect under ignorance of its exact initial conditions. This procedure works in the same manner for both classical and quantum physics. (3) There is no cogent reason to take the parameters that enter into the (deterministic) dynamical equations of physics to refer to properties of the physical systems. Granting an ontological status to parameters such as mass, charge, wave functions and the like does not lead to a gain in explanation, but only to artificial problems. Against this background, I argue that there is no conflict between determinism in physics and free will (on whatever conception of free will), and, in general, point out the limits of science when it comes to the central metaphysical issues.